A low power miniaturized CMOS-based continuous glucose monitoring system

Abstract

This paper presents the design and fabrication of a highly-miniaturized system for continuous glucose monitoring which holds great promise for patients inflicted with diabetes mellitus. To achieve the realization of a truly implantable system, a variety of issues such as robust electrochemical sensor design, miniaturization of the electronic components and counteracting biofouling and negative tissue response need to be addressed. In this report, we present a highly-miniaturized transcutaneous continuous glucose monitoring system which holistically addresses the aforementioned tribulations associated with implantable devices. Specifically, a high performance amperometric electrochemical glucose sensor is integrated with custom designed complementary metal-oxide-semiconductor electronics. The fabricated electrochemical sensor is Clark-based, and employs stratification of five functional layers to achieve a linear response within the physiological range of glucose concentration (2–22 mM). Furthermore, the sensor is encased with a thick polyvinyl alcohol (PVA) hydrogel containing poly(lactic-co-glycolic acid) (PLGA) microspheres which provides continuous, localized delivery of dexamethasone utilized to combat inflammation and fibrosis. Such miniature size (0.665 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and low power operation (140 μW) of the electronic system render it ideal for continuous glucose monitoring devices and other metabolic sensing systems.